Trends in heterocyclic chemistry. 10:67-72




Until 1995, all papers that claimed preparation or further study with monoiodo-8-quinolinol were really working with the 7-iodo isomer. Of the 83 relevant citations 67 dealt with incorrect structural assignments, 13 were critiqued due to errors made in synthesis and interpretation, and 9 had the correct structural assignments. This literature review made the following conclusions apparent. 1. Prototropic forms of 8- quinolinol influence orientation of electrophiles. 2. Under strong acidic conditions, the 5 position is favored. 3. Under mild acidic conditions, mixtures of 5 and 7 substituted compounds are formed. 4. Under basic conditions, the incoming electrophile favors the 7 position. 5. When the phenolic group is etherified or complexed with metals, only 5 substitution takes place, and 7 substitution occurs only after the 5 position is filled. 6. NXS is generally a superior halogenating agent than elemental halogen. 7. In order to avoid rearrangements, the more electronegative group should be put into the desired position followed by the less electronegative substituent

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